The present invention relates to a stationary dredging apparatus for automatically removing sand and silt from waterways and more particularly to self-cleaning stationary dredging apparatus.
In U.S. Pat. No. 3,638,432 which issued to the present applicant, a stationary dredge is disclosed in which a generally horizontal pipe is laid on the bottom of the waterway which is connected to the suction line of a pump. The horizontal line is provided with a plurality of perforations into which sand and silt are drawn by the suction of the pump. Clear water, that is water that is clear of sand and silt, is supplied to the horizontal line near the perforations closest to the connection to the pump to dilute the slurry passing through the perforated pipe and thereby reduce clogging. One disadvantage of this system is that when used in areas having high kelp growth or where a large amount of non-granular debris such as cans, bottles or water-logged driftwood, for example, have settled on the bottom, these non-granular debris are drawn by suction over the perforations, thereby clogging them. This same disadvantage also pertains to other types of silt removing, perforated lines which rest on the bottom of a waterway.